The present invention concerns an improved process for the production of magnetic materials and more particularly of materials of the garnet type, the grain size of which is such that no grain has a diameter larger than 1 micron. It is well known that the use of magnetic materials at ever increasing frequencies has led to attempts to obtain polycrystalline materials consisting of ever smaller grains, so as to approach as closely as possible the theoretical density of the bulk material, after sintering. It is known that the line width is smaller in proportion as the product is denser. In addition, the high power behaviour of ferrite devices is better in proportion as the grain size of the material employed is smaller. Grains of a dimension equal to or smaller than 1 micron are currently obtained by milling coarser crystallites. This operation, which may take several tens of hours, is a considerable disadvantage when the production of this type of material is concerned.
The present invention consists essentially in a process which involves no mechanical milling step and the various manufacturing steps of which are such as to prevent any growth of the crystallites, which can be obtained with very small dimensions by coprecipitation of metal salts under appropriate conditions.